2D sail simulations

james.conger · January 27, 2014, 12:11

Those of you with an interest in sailing might find these 2D simulations interesting. The cases so far are limited to single sails in close-hauled situations. The simulations with two sails are in progress. The focus is in understanding what drives sail trim.

STL models are generated using Python. Mesh generation uses blockMesh and snappyHexMesh. simpleFoam is used for Reynolds averaged results. The sample utility extracts profile data that is post processed using Python to evaluate the net forces.

Link:
https://sites.google.com/site/sailcfd/

The fun part of this is validating the results using a real sailboat. Time to collect some more data...

jherb · March 2, 2014, 10:44

Hello Jim,

thank you for sharing this link. Do you plan to share your (python) code and/or the OpenFOAM input files? These would be really interesting.

One question I have now is: How did you set your boundary conditions for the velocities to get the different angles of attack? Did you rotate the sails or change the boundary conditions? How does you "wind tunnel" looks like?

Best regards,
Joachim

james.conger · March 2, 2014, 12:07

Good suggestion to post an example OpenFOAM case. I'll pick an example case and put it on:

https://sites.google.com/site/sailcfd/

My Python scripts are not worthy of public release. They are just little utilities I use to tie together OpenFOAM elements, cutting down the manual chores.

And yes, I create one sail model and then run it changing the boundary conditions to simulate changes in wind speed and direction. I then create a new sail model for a different sail shape or trim and do it all over again. It ends up being hundreds of cases to explore even simple issues.

Recently we measured the amount of force needed to move the test boat at different speeds. Comparison of predicted vs. actual boat speed and heel is shown at the above link. This provides a measure of confidence that the OpenFOAM predictions of forward and heeling force are reasonable, as the real boat appears to perform on average as predicted. There is inevitably a lot of scatter in the test data, so more data collection is planned, once the winds pick up...

Giulio_cst · December 11, 2014, 08:30

Hi all,

I'm really interested in what this topic is about but unfortunately i can't see the links you have posted. My master thesis is about the study on the interaction between two ( or more ) sailboats and i'm having lots of problem doing my first 3D mesh. Is it my fault or, for some reason, these links are really no more valid?

Best Regards
G.

jherb · December 11, 2014, 08:35

These web pages (which were very interesting) seem to have gone ;-( I also do not see them anymore (since a few weeks)

January 27, 2014, 12:11	2D sail simulations	#1
james.conger New Member Jim Conger Join Date: Jan 2014 Location: California, USA Posts: 21 Rep Power: 12	Those of you with an interest in sailing might find these 2D simulations interesting. The cases so far are limited to single sails in close-hauled situations. The simulations with two sails are in progress. The focus is in understanding what drives sail trim. STL models are generated using Python. Mesh generation uses blockMesh and snappyHexMesh. simpleFoam is used for Reynolds averaged results. The sample utility extracts profile data that is post processed using Python to evaluate the net forces. Link: https://sites.google.com/site/sailcfd/ The fun part of this is validating the results using a real sailboat. Time to collect some more data... louisgag and jherb like this.

March 2, 2014, 12:07	Sail simulations	#3
james.conger New Member Jim Conger Join Date: Jan 2014 Location: California, USA Posts: 21 Rep Power: 12	Good suggestion to post an example OpenFOAM case. I'll pick an example case and put it on: https://sites.google.com/site/sailcfd/ My Python scripts are not worthy of public release. They are just little utilities I use to tie together OpenFOAM elements, cutting down the manual chores. And yes, I create one sail model and then run it changing the boundary conditions to simulate changes in wind speed and direction. I then create a new sail model for a different sail shape or trim and do it all over again. It ends up being hundreds of cases to explore even simple issues. Recently we measured the amount of force needed to move the test boat at different speeds. Comparison of predicted vs. actual boat speed and heel is shown at the above link. This provides a measure of confidence that the OpenFOAM predictions of forward and heeling force are reasonable, as the real boat appears to perform on average as predicted. There is inevitably a lot of scatter in the test data, so more data collection is planned, once the winds pick up...

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March 2, 2014, 10:44		#2
jherb Senior Member Joachim Herb Join Date: Sep 2010 Posts: 650 Rep Power: 21	Hello Jim, thank you for sharing this link. Do you plan to share your (python) code and/or the OpenFOAM input files? These would be really interesting. One question I have now is: How did you set your boundary conditions for the velocities to get the different angles of attack? Did you rotate the sails or change the boundary conditions? How does you "wind tunnel" looks like? Best regards, Joachim

December 11, 2014, 08:30		#4
Giulio_cst New Member Giulio Castellano Join Date: Nov 2014 Posts: 3 Rep Power: 11	Hi all, I'm really interested in what this topic is about but unfortunately i can't see the links you have posted. My master thesis is about the study on the interaction between two ( or more ) sailboats and i'm having lots of problem doing my first 3D mesh. Is it my fault or, for some reason, these links are really no more valid? Best Regards G.

December 11, 2014, 08:35		#5
jherb Senior Member Joachim Herb Join Date: Sep 2010 Posts: 650 Rep Power: 21	These web pages (which were very interesting) seem to have gone ;-( I also do not see them anymore (since a few weeks)